The study, which confirmed the results of other, smaller studies, addressed pain in general, but the researchers also discussed the pain associated with chronic pain conditions, like arthritis and other rheumatic diseases.

In addressing arthritis, the researchers acknowledged the chicken-or-egg conundrum. Stone and Broderick say that such debilitating diseases could keep patients from participating in physical activity, which makes them prone to weight gain.

But even when they controlled for the presence of a chronic condition, like arthritis, the association still remained, although it was “substantially reduced.”

Also noteworthy is that the effect of weight on pain intensified as the age group of the respondents increased.

“This [pain intensification] could suggest a developmental process,” Broderick says. “If you just think about it in terms of inflammation, if people are carrying excess weight and that is triggering an inflammation process – that could explain why the longer people are walking around with excess weight the more the inflammatory process is causing damage.”

That inflammatory process could be the handiwork of hormones – in particular, one called leptin. It’s best known as a hunger-regulating hormone released by fat tissue, but recent studies have linked increased leptin levels with inflammation and pain in people with arthritis. Stone and Broderick acknowledged leptin as a possible reason for the link between weight and pain in their study.

“There is emerging research that suggests that having more fat cells and fat tissue in the body triggers an inflammatory response and inflammation [which] could then contribute to pain for one reason or another,” Broderick explains.

Lawrence J. Cheskin, MD, director of the Johns Hopkins Weight Management Center in Baltimore, applauds the researchers for working to understand what is driving pain in people who are overweight and obese, but he says the bottom line remains the same for patients.

“The fact is – if you are obese for whatever set of reasons – you are more likely to have daily pain,” he says.

While he knows it can be daunting, he says losing weight is critical. “In addition to everything else we already know – [losing weight] has a good chance to make it less likely for you to have daily pain,” Dr. Cheskin says. “Someone with early arthritis – who is starting to get discomfort and [have limited movement] – if they lose weight they can do more because they weigh less and their arthritis may not progress to such disabling levels.”